Detecting differences at the cellular level is an ongoing problem which, if successfully addressed, could help solve several prevalent ailments, including cancers and prenatal diseases.
Normal tissue function requires appropriate cell positioning and directional motion. This property, known as chirality, can be altered by genetic and environmental factors, leading to, for example, birth defects and tumor formation.
Current methods to diagnose cancer are based on biomarkers, imaging, and analysis of tissue specimens. In most cases, the findings from one assay (such as imaging) are corroborated by other assays (such as pathological evaluation of biopsy samples).
Chirality is often known as left-right (LR) asymmetry in the development of numerous living organisms, including climbing plants (1), helices of snail shells (2), and the human body (3, 6). Genetic diseases and prenatal exposure to teratogens (4) can cause birth defects in laterality. The LR asymmetry has been studied in animal embryos, which are difficult to control and are not necessarily representative of human condition (7, 8). Recent studies focused on directional nodal flow driven by primary cilia (9-11), pH gradients resulting from asymmetric expression of ion channels (12, 13), and asymmetric vesicular transport via myosin 1D along actin cable networks (14-16).
The initiation of chirality in development is often first observed in populations of cells of the same type, such as snail embryonic cells at 4-cell and 8-cell stages and mouse cells at embryonic nodes. The establishment of chirality within such cell clusters may rely on some intracellular structure, such as the hypothetical F-molecule or actin/microtubule cytoskeleton (17, 18) that can distinguish left from right by orienting the 3rd axis with respect to predetermined dorsal-ventral and anterior-posterior axes. In addition, during development, the specification and self-organization of migrating cells are mediated by physical boundaries imposed by the extracellular matrix and the surrounding cells and tissues.